Method of preparing a stable colloid of submicron particles

ABSTRACT

The invention provides submicron particles. The invention further provides submicron particles which are dispersed in an aqueous colloid. The invention further provides a method of forming the stable dispersion which includes providing an ion exchange resin, loading the ion exchange resin with an ion, treating the loaded resin to form nanoscale particles. The invention further provides fluidizing the resin and particles to form an aqueous stable colloid.

This is a continuation of application Ser. No. 07/910,803, filed Jul. 9,1992, now U.S. Pat. No. 5,362,417.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the formation of a stable colloidaldispersion of fine particles. More particularly, the invention relatesto the formation of nanocomposites.

More specifically, the invention relates to the formation of continuousfilms of submicron particles.

2. Description of the Prior Art

Prior art formation of submicron or nanometer structures havepredominantly included the formation of large particles which aresubsequently ground or milled until particles of the desired size areachieved. The grinding and milling times associated with the formationof such particles ranged from 120 to 2900 hours.

A method of forming dry magnetic submicron particles by precipitation ofa magnetic oxide in an ion exchange resin is discussed and exemplifiedby Ziolo in U.S. Pat. No. 4,474,866. According to the method employed,an ion exchange resin is loaded with a magnetic ion. The resin is thenrecovered and dried. The magnetic polymer resin is then micronized toform a fine magnetic powder. The dry magnetic particles formed accordingto Ziolo, U.S. Pat. No. 4,474,866, like other typical prior artmaterials, could not be directly suspended in an aqueous medium to forma stable colloid.

Difficulties have been encountered in forming and maintaining nanoscalematerials due to the tendency of the particles to aggregate to reducethe energy associated with the high area to volume ratio. Thisaggregation leads to additional difficulties in the preparation ofhomogeneous dispersions and thin continuous films produced therefrom.

Prior art formation of films of submicron particles have required thespreading of fine particles which resulted in uneven and noncontinuousfilms. In addition, if the particles were dispersed in a fluid medium,upon evaporation of the fluid medium, film properties were not continousbut were individual islands of particulate material. By contrast, thefluids of the present material are a composite of a crushed matrixmaterial and nanometer particles in an aqueous vehicle. Upon evaporationof the aqueous vehicle in the present invention, the particles are leftin a continuous film joined by a network of this crushed resin material.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to overcome these andother difficulties encountered in the prior art.

It is also an object of the present invention to provide a method offorming submicron particles without the use of extended grinding ormilling times.

A further object of the present invention is to provide a method offorming an aqueous suspension or colloid of submicron particles.

Another object of the present invention is to provide an aqueous colloidof fine particles capable of forming continuous films of submicronparticles.

Another object of the present invention is to proved small or nanoscaleparticles in a medium or matrix that can be easily crushed or micronizedto form a dry powder for dispersion in a fluid or solid, for example apolymer.

These and other objects have been achieved by the present inventionwhich relates to a process for preparing a stable colloid of fineparticles which comprises 1) preparing an ion exchange crosslinked resinmatrix; 2) loading the resin matrix with an ion; 3) treating the loadedresin matrix to cause an in-situ precipitation of fine particles; 4)repeating the ion exchange process until the matrix ruptures; and 5)optionally, micronizing the mixture of resin and precipitated particlesin a fluid to form the stable colloid of submicron particles where anion exchange resin of larger than submicron dimensions is used oralternatively, where smaller submicron particles are desired. For thepurposes of the present invention, colloid is defined as a stablehomogeneous dispersion of particles in a fluid medium.

When using a submicron resin, no micronization step is required to formthe stable colloid. A micronization step may however, be used with asubmicron resin if smaller submicron particles are desired.

When a micronization step is necessary, the present inventiondrastically reduces the grinding or milling time to a range ofapproximately 30 to about 180 minutes. According to the presentinvention, submicron particles may be produced by building from themolecular level rather than grinding larger particles down to formsmaller particles.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of hollow fiber ultrafiltration.

FIG. 2 illustrates membrane separation application based on particlesize.

FIG. 3 illustrates direct coloring of the resin matrix.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the invention, a crosslinked polymer resin matrix havingchemically addressable sites is used to prepare the colloid. Such amatrix is provided by an ion exchange resin. The majority of organic ionexchange resins are based upon a matrix of crosslinked polystyrene whichprovides a chemically and physically robust micro structure of the typeneeded to produce the fine particulate. A preferred resin is apolystyrene sulfonic acid (PSSA) ion exchange resin crosslinked fromabout 1 to 16% with divinylbenzene. More preferably, a 4 to 8%divinylbenzene crosslinked sulfonated polystyrene.

Illustrative examples of suitable ion exchange resins include thosepolymers possessing chemically addressable sites dispersed throughouttheir matrix, or on their surface, which sites can be used to generatean ionic component in situ.

Specific examples of these resins include sulfonated polystyrenes,R--CH₂ SO₃ --H⁺ strongly acidic phenolics, weakly acidic acrylics,R--COO--Na⁺ wherein R is an alkyl group, weakly acidic chelatingpolystyrenes and the like, with strongly acidic sulfonated polystyrenesbeing preferred. In addition, anionic exchange resins such as BakerIONAC NA-38, Baker IONAC A-554, Dowex® SBR, Amberlite® IRA-400 andDowex® IX8-100 may also be used. Other suitable resins can be selectedby one having ordinary skill in the art provided that they are colorlessor have only slight color density, have a non-interfering color, andproviding they achieve the objectives of the present invention.

The resin matrix is preferably capable of withstanding repeated cyclesof drying, swelling, and de-swelling and preferably will not decomposethermally below 120° C. The resin is preferably unaffected by exposureto strong acids, bases or redox solutions.

The resin may be of an analytical or an industrial grade. Aside fromdifferences in cost and size, the industrial grade resins have morecolor than the analytical grades. Most of the color associated withindustrial grade resins is temporary and is easily removed by solventwashing, usually with water. After washing, the industrial grade resinretains a weak amber color similar to the analytical grade.

Resin beads may be about 20 to about 500 mesh and are preferably fromabout 20 to about 400 mesh size or between about 850 and about 38microns. More preferably, the resin beads are from about 200 to about400 mesh or between about 75 and 38 microns. The larger size beads havetwo advantages over the smaller beads. First, the processing time isshorter when using the larger beads due to faster settling rates andease of decanting. Second, the larger beads are mechanically weaker thanthe smaller bead due to greater osmotic shock effects during theirmanufacture. Thus, low optical density material prepared from the largerbeads crushes and presumably micronizes more easily than those made fromthe smaller beads. Despite its weaker mechanical strength, the lowercost larger resin retains its ion-exchange capability through and evenbeyond ten-cycles of loading.

Commercial ion exchange resins for use in the invention includepolystyrene sulfonic acid ion exchange resins which may be obtained fromsuch manufacturers as Rohm and Haas and Dow Chemical.

In addition to cost and color, homogeneity of the resin with respect tocross-link density and site sulfonation should be considered inselecting an appropriate resin. These aspects affect the dispersioncharacteristics of particle size, shape and distribution which in turnalter the optical characteristics of the composite.

Alternatively, the resin may be selected in a submicron size so that noadditional micronization step is necessary. Examples of such a matrixinclude a submicron sulfonated polystyrene resin, designated SSPR forthe purposes of the present invention, which is available from Rohm &Haas in emulsion form. Additional submicron resins which would beappropriate for use in the present invention include any submicronresins which do not interfere with the characteristics of the materialdisclosed herein.

Once a resin is selected, the resin matrix is next loaded with theprecipitate precursor ion. In the case of the magnetic colloid this maybe several different ions including ferrous or ferric ions in a mannerdescribed in U.S. Pat. No. 4,474,886 to Ziolo. In the case of anon-magnetic colloid, this may include ions of, for example, sulfur,selenium, gold, barium, cadmium, copper, silver, manganese, molybdenum,zirconium, gallium, arsenic, indium, tin, lead, germanium, dysprosium,uranium, aluminum, platinum, palladium, iridium, rhodium, cobalt, iron,nickel, rhenium, tungsten, lanthanum and the like.

Next, the loaded resin is treated so as to cause an in-situprecipitation of the material desired for dispersion. Cadmium sulfide awell known semiconductor material, for example, may be precipitated inthis manner. The nanometer particles may be precipitated as compounds,for example as copper sulfide or in their elemental forms.

Once the composite material has been formed, the ion exchange processand subsequent formation of particles may then be repeated several timesto achieve higher loading of particles. As the number of particlesincreases or their size increases the crosslinked polymer matrix becomesstressed and eventually ruptures. In a typical ion exchange resin,stress may occur after the first loading.

Micronization, by for example, ball-milling of this composite in astable medium or vehicle will lead to the formation of the stabledispersion of the composite material in about 30 to about 180 minutes. Asuitable vehicle is any vehicle which allows dispersion including forexample water and water miscible materials and like solvents, such asmethanol and the like. The vehicle may further include any materialwhich will not adversely effect the desired mechanical, electrical oroptical properties, for example, water soluble polymers.

Fluidization as used herein is defined as the formation of a liquidthrough micronization of the polymeric matrix containing the particles.Micronization may be accomplished by attrition, air attrition followedby dispersion in water, shaking, milling, ball milling, shaking or ballmilling directly in water or the like. Shaking or ball milling arepreferred. Coarse particles may be removed by filtration orcentrifugation. The average micronization time is from about 30 to about180 minutes.

With the use of a submicron resin a stable colloid will be formed uponprecipitation and no further micronization step will be necessary. Anadditional micronization step may be carried out if a smaller particlesize colloid is desired.

In the case of submicron resins, the ultrafiltration technique is usedin place of conventional ion exchange techniques to process the resinbecause of the very small size of the resin beads. The submicron resinbeads may be suspended in an aqueous colloidal form prior toincorporation of the ions, thus resulting in a stable colloidaldispersion of the resin and particles. Alternatively, the resin beadsmay be removed and dried to form a dry nanocomposite.

Ultrafiltration is a pressure-activated membrane filtration processcapable of performing a variety of selective molecular separations. Fora discussion of this technology see Breslau, B. R., "Ultrafiltration,Theory and Practice," paper presented at the 1982 Corn RefinersAssociation Scientific Conference, Lincolnshire, Ill., Jun. 16-18, 1982,which is incorporated herein by reference. In ultrafiltration, theprocess fluid flows across a membrane with pore diameters in the rangeof 10 to 200 Angstroms, as shown in FIG. 1. Solvents and species whosemolecular size and weight are below the molecular weight cut-off willpermeate through the membrane and emerge as an ultrafiltrate, whilerejected species are progressively concentrated in the process stream.Ultrafiltration differs from reverse osmosis in that it employs a more"porous" membrane which will not retain low molecular weight speciessuch as solvent molecules. FIG. 2 illustrates the membrane separationapplication based on particle size. Ultrafiltration covers the range of10⁻³ to 10² microns.

At the heart of the ROMICON® ultrafiltration system is the hollow fiber.These hollow fibers are constructed on non-cellulosic, syntheticpolymers. They are anisotropic and have a very tight skin on theinternal surface supported by a sponge-like outer structure. Theextremely thick wall of the hollow fiber gives it the strength neededfor long service. The skin or active membrane is 0.1 microns thick andany species passing through the skin readily passes through the outerstructure. Any buildup of foreign matter which occurs, therefore, issolely on the skin and not in the sponge-like outer support.

The self-supporting structure of the hollow fiber enables the use of abackflushing technique to maintain continuous high average flux ratesthrough the fibers. Backflushing forces foreign materials andflux-inhibiting layers from the membrane surface. Because flow occurs onthe inside of the hollow fiber under controlled fluid managementconditions, high shear forces exist at the membrane surface thatminimize concentration polarization by rejected solutes. The rejectedsolutes are continuously concentrated upstream in the process, while lowmolecular weight solutes and solvent permeate through the membrane.

The ROMICON® hollow fibers are housed in a cartridge (shell and tubegeometry). Shell and tube geometry refers to a construction whereby thefibers are held within an external cartridge, making possible flowthrough the fibers or flow around the fibers by feeding fluid into theexternal cartridge, as explained below. Each cartridge contains twoprocess and two permeate ports. The process ports feed directly to thelumen of the fibers, while the permeate ports feed directly to thecartridge shell. Flow through these ports can be completely controlledand switched from one mode of operation to another. The cartridge can beoperated at high temperatures due to the non-cellulosic nature of theROMICON® hollow fiber and in the wide pH range encountered in thepreparation of these nanometer particles.

The composite resin beads as described above may be dried prior tomicronization and then subsequently micronized to produce a dry powdercomposite for dispersion in a fluid or solid, for example, a polymer.This dispersion of crushed composite and fluid or solid may subsequentlybe used in film formation as described below.

The materials described herein may be dyed or may coexist with thecolloidal suspension of a second constituent which may be coloredpigment. Colored pigment may be added to the mix along with thecomposite to achieve the desired color. In addition, since ion exchangecapability is maintained in the composite itself, color may also beintroduced directly in the polymer matrix by ion exchanging dyes orother chromophores into the resin.

There can be selected as pigments, known magenta, cyan, yellow pigmentsand mixtures thereof, as well as red, green, or blue pigments, ormixtures thereof, and the like.

Illustrative examples of magenta materials that may be used as pigments,include for example, 2,9-dimethyl-substituted quinacridone andanthraquinone dye identified in the Color Index as CI 60710, CIDispersed Red 15, diazo dye identified in the Color Index as CI 26050,CI Solvent Red 19, and the like. Illustrative examples of cyan materialsthat may be used as pigments include coppertetra-4(octadecyl-sulfonamido) phthalocyanine, X-copper phthalocyaninepigment listed in the Color Index as CI 74160, CI Pigment Blue, andAnthradanthrene Blue X2137, and the like. Illustrative examples ofyellow pigments that may be employed include diarylide yellow3,3-dichlorobenzidene acetoacetanilides, a monoazo pigment identified inthe Color Index as CI 12700, CI Solvent Yellow 16, a nitrophenyl aminesulfonamide identified in the Color Index as Foron yellow SE/GLN, CIdispersed yellow 33, 2,5-dimethoxy-4-sulfonanilidephenylazo-4'-chloro-2,5-dimethoxy aceto-acetanilide, permanent yellowFGL, and the like.

Illustrative examples of red materials useful as pigments include,cadmium red 150K, CI pigment red 108; lithol red, CI pigment red 49;lithol scarlet, CI pigment red 4301L; toluidene red, CI pigment red 3;and the like. Examples of green pigments include, chrome green, CIpigment green 15; chrome green lake, CI pigment green 18; chrome intragreen, CI pigment green 21; phthalocyanine green, CI pigment green 7;and the like. Examples of blue pigments include, phthalocyanine blue, CIpigment blue 15; prussion blue, CI pigment blue 27; ultramarine blue, CIpigment blue 29, and the like.

The color pigments, namely, red, green, blue, cyan, magenta and yellowpigments are generally present in an amount of from about 1 to about 20%and preferably from about 2 to about 10%. The pigment is introducedthrough attrition, air attrition, shaking, milling, ball milling or thelike. The pigment particle size is selected so that it will notinterfere with any of the desired material characteristics. Theparticles are preferably submicron in size but may be larger dependingupon the intended color application. The ability to manipulate the sizeof the pigment particle to achieve the desired color result would bewith the skill of the practitioner in the art.

Examples of suitable water soluble dyes include Bernacid Red 2BMN,Pontamine Brilliant Bond Blue A, BASF X-34, Pontamine, Food Black 2,Carodirect Turquoise FBL Supra Conc. (Direct Blue 199), available fromCarolina Color and Chemical, Special Fast Turquoise 8GL Liquid (DirectBlue 86), available from Mobay Chemical, Intrabond Liquid Turquoise GLL(Direct Blue 86), available from Crompton and Knowles, CibracronBrilliant Red 38-A (Reactive Red 4), available from Aldrich Chemical,Drimarene Brilliant Red X-2B (Reactive Red 56), available from Pylam,Inc., Levafix Brilliant Red E-4B, available from Mobay Chemical, LevafixBrilliant Red E-6BA, available from Mobay Chemical, Procion Red H8B(Reactive Red 31), available from ICI America, Pylam Certified D&C Red#28 (Acid Red 92), available from Pylam, Direct Brill Pink B GroundCrude, available from Crompton & Knowles, Cartasol Yellow GTF Presscake,available from Sandoz, Inc., Tartrazine Extra Conc. (FD&C Yellow #5,Acid Yellow 23), available from Sandoz, Carodirect Yellow RL (DirectYellow 86), available from Carolina Color and Chemical, Cartasol YellowGTF Liquid Special 110, available from Sandoz, Inc., D&C Yellow #10(Acid Yellow 3), available from Tricon, Yellow Shade 16948, availablefrom Tricon, Basacid Black X34, available from BASF, Carta Black 2GT,available from Sandoz, Inc., Neozapon Red 492 (BASF), Orasol Red G(Ciba-Geigy), Direct Brilliant Pink B (Crompton-Knolls), Aizen SpilonRed C-BH (Hodagaya Chemical Company), Kayanol Red 3BL (Nippon KayakuCompany), Levanol Brilliant Red 3BW (Mobay Chemical Company), LevadermLemon Yellow (Mobay Chemical Company), Spirit Fast Yellow 3G, AizenSpilon Yellow C-GNH (Hodagaya Chemical Company), Sirius Supra Yellow GD167, Cartasol Brilliant Yellow 4GF (Sandoz), Pergasol Yellow CGP(Ciba-Geigy), Orasol Black RL (Ciba-Geigy), Orasol Black RLP(Ciba-Geigy), Savinyl Black RLS (Sandoz), Dermacarbon 2GT (Sandoz),Pyrazol Black BG (ICI), Morfast Black Conc A (Morton-Thiokol), DiazolBlack RN Quad (ICI), Orasol Blue GN (Ciba-Geigy), Savinyl Blue GLS(Sandoz), Luxol Blue MBSN (Morton-Thiokol), Sevron Blue 5GMF (ICI),Basacid Blue 750 (BASF), Levafix Brilliant Yellow E-GA, Levafix YellowE2RA, Levafix Black EB, Levafix Black E-2G, Levafix Black P-36A, LevafixBlack PN-L, Levafix Brilliant Red E6BA, and Levafix Brilliant Blue EFFA,available from Bayer, Procion Turquoise PA, Procion Turquoise HA,Procion Turquoise H-5G, Procion Turquoise H-7G, Procion Red MX-5B,Procion Red MX 8B GNS, Procion Red G, Procion Yellow MX-8G, ProcionBlack H-EXL, Procion Black P-N, Procion Blue MX-R, Procion Blue MX-4GD,Procion Blue MX-G, and Procion Blue MX-2GN, available from ICI, CibacronRed F-B, Cibacron Black BG, Lanasol Black B, Lanasol Red 5B, Lanasol RedB, and Lanasol Yellow 4G, available from Ciba-Geigy, Basilen Black P-BR,Basilen Yellow EG, Basilen Brilliant Yellow P-3GN, Basilen Yellow M-6GD,Basilen Brilliant Red P-3B, Basilen Scarlet E-2G, Basilen Red E-B,Basilen Red E-7B, Basilen Red M-5B, Basilen Blue E-R, Basilen BrilliantBlue P-3R, Basilen Black P-BR, Basilen Turquoise Blue P-GR, BasilenTurquoise M-2G, Basilen Turquoise E-G, and Basilen Green E-6B, availablefrom BASF, Sumifix Turquoise Blue G, Sumifix Turquoise Blue H-GF,Sumifix Black B, Sumifix Black H-BG, Sumifix Yellow 2GC, Sumifix SupraScarlet 2GF, and Sumifix Brilliant Red 5BF, available from SumitomoChemical Company, Intracron Yellow C-8G, Intracron Red C-8B, IntracronTurquoise Blue GE, INtracron Turquoise HA, and Intracron Black RL,available from Crompton and Knowles, Dyes and Chemicals Division, andthe like. Dyes that are invisible to the naked eye but detectable whenexposed to radiation outside the visible wavelength range (such asultraviolet or infrared radiation), such as dansyl-lysine,N-(2-aminoethyl)-4-amino-3,6-disulfo-1,8-dinaphthalimide dipotassiumsalt, N-(2-aminopentyl)-4-amino-3,6-disulfo-1,8-dinaphthalimidedipotassium salt, Cascade Blue ethylenediamine trisodium salt (availablefrom Molecular Proes, Inc.), Cascade Blue cadaverine trisodium salt(available from Molecular Proes, Inc.), bisdiazinyl derivatives of4,4'-diaminostilbene-2,2'-disulfonic acid, amide derivatives of4,4'-diaminostilbene-2,2'-disulfonic acid, phenylurea derivatives of4,4'-disubstituted stilbene-2,2'-disulfonic acid, mono- ordi-naphthyltriazole derivatives of 4,4'-disubstituted stilbenedisulfonic acid, derivatives of benzithiazole, derivatives ofbenzoxazole, derivatives of benziminazole, derivatives of coumarin,derivatives of pyrazolines containing sulfonic acid groups,4,4'-bis(triazin-2-ylamino)stilbene-2,2'-disulfonic acids,2-(stilben-4-yl)naphthotriazoles, 2-(4-phenylstilben-4-yl)benzoxazoles,4,4-bis(triazo-2-yl)stilbene-2,2'-disulfonic acids,1,4-bis(styryl)biphenyls, 1,3-diphenyl-2-pyrazolines, bis(benzazol-2-yl)derivatives, 3-phenyl-7-(triazin-2-yl)coumarins, carbostyrils,naphthalimides, 3,7-diaminodibenzothiophen-2,8-disulfonicacid-5,5-dioxide, other commercially available materials, such as C.I.Fluorescent Brightener No. 28 (C.I. 40622), the fluorescent seriesLeucophor B-302, BMB (C.I. 290), BCR, BS, and the like (available fromLeucophor), and the like, are also suitable.

The dye is present in the composition in any effective amount, typicallyfrom about 1 to about 20% by weight, and preferably from about 2 toabout 10% by weight, although the amount can be outside of this range.As will be recognized by the skilled artisan, the above listing of dyesand pigments are not intended to be limiting. Additional dyes andpigments for use in the present invention are readily recognizable bythe skilled artisan.

Since ion exchange capability is maintained in the composite itself,color may also be introduced directly in the polymer matrix by ionexchanging dyes or other chromophores in the resin. Two examples of thisapproach are illustrated in FIG. 3. The first two direct coloringexamples shown in FIG. 3 illustrate ion exchange of cationic dyes toproduce red and black resins respectively.

In addition, again using the ion exchange capabilities of the resin,direct coloration can be achieved by the introduction of a metal thatcan form chromophores with known chelating agents and other chromophoreproducing materials. The second two direct coloring examples of FIG. 3illustrate this method of direct precipitation of chromophores in theresin using iron(II) bipyridyl and nickel dimethylglyoxine to form redresins. Direct coloration has been found to be highly efficient andrapid using the micronized form of the composite. Any known dye may beused which is capable of ionic exchange with the resin, as describedabove. Methods of direct coloration are described in F. Helfferich, "IonExchange", McGraw-Hill, NY 1962, and R. Paterson, "An introduction toIon Exchange", Heyden and Son, Ltd., London, 1970, both of which areincorporated herein by reference.

Colored materials prepared as described above are stable toward settlingand do not separate color from the vehicle.

The materials as described herein may be used in the formation ofcontinuous films, surface coatings, thick films and free-standing films.Such films may be formed on any known substrate, for example glass,metal, selenium, silicon, quartz, fabric, fibers, paper and the like.Methods of forming these films preferably include evaporation, spincoating, dip coating, extrusion coating, gravure coating, roll coating,cast coating, brush coating, calender coating, meniscus coating,powdered resin coating, spray coating, electrostatic spray coating andby draw bar. Any known method of coating is acceptable. Examples ofvarious coating methods may be found, for example in G. L. Booth,"Coating Equipment and Processes" Lockwood Publishing, New York, 1970;the Kirk-Othmer Encyclopedia of Chemical Technology, 3rd. ed.,Wiley-Interscience, New York, 1979; and in "Ullmann's Encyclopedia ofIndustrial Chemistry," VCH Publishers, New York, 1991. Furthermore, thematerial of the invention may be mixed or otherwise added to known filmforming materials such as polymers, plastics and the like to cast orproduce films containing the material of the invention. Films formedfrom the material of the invention include for example mechanical,magnetic, optical or electronic device applications.

The following examples are illustrative of the invention embodiedherein.

EXAMPLE I

60 g of Dowex® 50X8-400 ion exchange resin, obtained from the AldrichChemical Co. (Milwaukee, Wis.), were washed clean in batch withconcentrated HCl, followed by washings with 0.1N NaOH, deionized water,methanol and finally deionized water.

38 g of BaCl₂ in 350 ml of H₂ O was then added to the washed resin andthe mixture stirred for 2 hours. The mixture was filtered and theprocedure repeated with another batch of BaCl₂ solution. The mixture wasthen filtered and the resin washed with deionized water, first through afilter and then in batch until the filtrate tested negative for bariumions using a sulfate test for barium. The resin was then filtered and asolution of 60 g of Na₂ SO₄ in 400 mls of H₂ O was added. The mixturewas stirred for 1.5 hours. The resin was filtered and washed clean withlarge amounts of deionized water then dried overnight at 110° C. to forma composite of ultra-fine particles of BaSO₄ in the ion exchange resin.Transmission electron microscopy revealed barium sulfate particulateabout 5 to 15 nm in size suspended in the resin. Elemental analysis forbarium showed the expected barium to sulfur (sulfonate) ratio of onehalf.

EXAMPLE II

An ultra-fine particle dispersion of copper sulfide in a polymer resinmatrix was formed by treating Dowex® 50X8-400 ion exchange resin fromthe Dow Chemical Co. (Midland, Mich.) with solutions of copper nitrateand soluble sulfide.

60 g of Dowex® 50X8-400 was washed as described in Example I, above andplaced in a 500 ml beaker equipped with magnetic stirrer and stirringbar. Next, 350 ml of water containing 90 g of Cu(NO₃)₂.6H₂ O was addedto the beaker and the contents stirred for one hour. The resin was thenfiltered and the procedure repeated a second time. The resin was thenthoroughly washed with deionized water until no free copper ions werefound in solution. The resin was filtered using a coarse glass fritfunnel and resuspended in a solution containing 85 g of Na₂ S.9H₂ O inabout 400 ml of water and stirred for about one hour at roomtemperature. The resulting dark colored resin was then filtered andagain washed with large amounts of deionized water until it was free ofexcess soluble sulfide. Electron microscopy of the microtomed resinrevealed CuS particles less than 20 nm dispersed throughout the resin.Elemental analysis for copper showed the expected copper sulfide tosulfonate sulfur ratio of about one half.

EXAMPLE III

A nanocomposite of the well-known semiconductor, cadmium sulfide, CdS,was prepared by following the procedure of Example II, except that 80 gof Cd(NO₃)₂ were used in place of the copper nitrate. The cadmiumsulfide was then precipitated in the ion exchange resin and processed asdescribed in Example II. In a separate experiment, the CdS wasprecipitated using a solution of 25 g of ammonium sulfide, (NH₄)₂ S, in300 g of water. The yellow/orange composite was then filtered andthoroughly rinsed with deionized water to remove soluble sulfide. Theresin was then dried at 110° C. overnight. The cadmium sulfide particlesin the resin ranged in size from about 0.1 to greater than 20 nmdepending on processing conditions.

EXAMPLE IV

60 g of Amberlite® IRP-69 ion exchange resin manufactured by Rohm andHaas Co. (Philadelphia, Pa.) was washed as described in Example I andplaced in a 500 ml beaker equipped with magnetic stirrer and stirringbar. The resin was then treated with a solution containing 40 g ofmanganese chloride in 350 ml of water and stirred for 2 hours. The resinwas filtered, and the procedure repeated a second time. The resin wasthen filtered and rinsed thoroughly with large amounts of deionizedwater. The resin was then suspended in 300 ml of deionized water in a500 ml beaker. 6 g of NaOH in 25 ml of deionized water was added to thebeaker with stirring to bring the pH to near 14. The suspension was thentreated with 10 ml of 30% H₂ O₂ diluted to 60 ml with deionized water ina dropwise fashion over a period of 30 minutes with continued stirring.The resin was then washed to neutral pH, filtered and dried overnight at110° C. to afford a composite of ultra-fine particle MnO₂ in polymer.The MnO₂ particle sizes in the resin ranged from about 0.2 to 20 nm asdetermined by transmission electron microscopy of microtomed samples ofthe composite.

EXAMPLE V

60 g of washed Dowex® 50X8-400 ion exchange resin were stirred for onehour in a solution containing 60 g of silver nitrate in 400 ml ofdeionized water. The resin was then filtered and treated a second timewith the silver nitrate solution. The resin was then washed with largeamounts of deionized water to remove all traces of free silver ion.Next, the resin was stirred in a sodium chloride solution of 50 g ofNaCl in 400 ml of deionized water for one hour. The resin was thenfiltered and dried overnight in a vacuum desiccator to form ananocomposite of silver chloride in polymer resin. Transmission electronmicroscopy and X-ray diffraction indicated silver chloride in a particlesize less than 20 nm.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only with a true scope and spirit ofthe invention being indicated by the following claims.

We claim:
 1. A method of forming a colloid dispersion of submicronparticles comprising:providing an ion exchange resin matrix; loadingsaid resin matrix with an ion; and treating the resin to cause in-situformation of submicron particles; and fluidizing said ion exchange resinand particles by micronization of the polymeric matrix in an aqueousmedium to form a stable colloid of said particles.
 2. The methodaccording to claim 1, wherein the fluidizing step includes micronizingsaid resin matrix and fine particles by ball milling.
 3. The methodaccording to claim 1, wherein the fluidizing step includes micronizingsaid resin matrix and fine particles by air attrition followed bydispersion in a fluid.
 4. The method according to claim 1, wherein thefluidizing step includes micronizing said resin matrix and fineparticles by shaking.
 5. The method according to claim 1, wherein theloading step is repeated a plurality of times before the fluidizing steptakes place.
 6. The method according to claim 5 wherein said loadingstep is repeated between about 5 and about 10 times.
 7. The methodaccording to claim 1, wherein said loading step is repeated until theresin matrix ruptures.
 8. The method according to claim 1, wherein saidion is selected from the group consisting of sulfur, selenium, gold,barium, cadmium, copper, silver, manganese, molybdenum, zirconium,gallium, arsenic, indium, tin, lead, germanium, dysprosium, uranium,aluminum, platinum, palladium, iridium, rhodium, cobalt, iron, nickel,rhenium, tungsten and lanthanum.
 9. The method according to claim 1,wherein said ion is cadmium and said fine particles are cadmium sulfide.10. The method according to claim 1, wherein said ion is barium and saidfine particles are barium sulfate.
 11. The method according to claim 1,wherein said ion is copper and said fine particles are copper sulfide.12. The method according to claim 1, wherein said ion is manganese andsaid fine particles are manganese oxide.
 13. The method according toclaim 1, wherein said ion is silver and said fine particles are silverchloride.
 14. The method according to claim 1, wherein said ion issilver and said fine particles are elemental silver.
 15. The methodaccording to claim 1, wherein said ion is gold and said fine particlesare gold.
 16. The method according to claim 1, wherein said ion isselenium and said fine particles are selenium.
 17. A method of forming acolloidal dispersion of fine particles comprising:providing a submicronion exchange resin which remains suspended in a fluid medium; loadingsaid resin with an ion; and treating the resin to cause in-situformation of submicron particles and form a stable colloid.
 18. Themethod according to claim 17, wherein the loading step is repeated aplurality of times.
 19. The method according to claim 18, wherein saidloading step is repeated between about 5 and about 10 times.
 20. Themethod according to claim 17, wherein said ion is selected from thegroup consisting of sulfur, selenium, gold, barium, cadmium, copper,silver, manganese, molybdenum, zirconium, gallium, arsenic, indium, tin,lead, germanium, dysprosium, uranium, aluminum, platinum, palladium,iridium, rhodium, cobalt, iron, nickel, rhenium, tungsten and lanthanum.21. The method according to claim 17, wherein said loading step isrepeated until the resin matrix ruptures.
 22. The method according toclaim 17, wherein said ion is cadmium and said fine particles arecadmium sulfide.
 23. The method according to claim 17, wherein said ionis barium and said fine particles are barium sulfate.
 24. The methodaccording to claim 17, wherein said ion is copper and said fineparticles are copper sulfide.
 25. The method according to claim 17,wherein said ion is manganese and said fine particles are manganeseoxide.
 26. The method according to claim 17, wherein said ion is silverand said fine particles are silver chloride.
 27. The method according toclaim 17, wherein said ion is silver and said fine particles areelemental silver.
 28. The method according to claim 17, wherein said ionis gold and said fine particles are gold.
 29. The method according toclaim 17, wherein said ion is selenium and said fine particles areselenium.
 30. The method according to claim 17, wherein the fluid mediumis an aqueous medium.
 31. A method of forming nanoscale compositeparticles comprising:providing an ion exchange resin matrix; loadingsaid resin with an ion; treating the resin to cause in-situ formation ofsubmicron particles; drying the composite of resin beads and submicronparticles; and micronizing the composite to form a dry powder.
 32. Themethod according to claim 31, wherein said resin matrix and fineparticles are micronized by ball milling.
 33. The method according toclaim 31, wherein said resin matrix and fine particles are micronized byair attrition followed by dispersion in a fluid.
 34. The methodaccording to claim 31, wherein said resin matrix and fine particles aremicronized by shaking.
 35. The method according to claim 31, wherein theloading step is repeated a plurality of times before the drying steptakes place.
 36. The method according to claim 35, wherein said loadingstep is repeated between about 5 and about 10 times.
 37. The methodaccording to claim 31, wherein said loading step is repeated until theresin matrix ruptures.
 38. The method according to claim 31, whereinsaid ion is selected from the group consisting of sulfur, selenium,gold, barium, cadmium, copper, silver, manganese, molybdenum, zirconium,gallium, arsenic, indium, tin, lead, germanium, dysprosium, uranium,aluminum, platinum, palladium, iridium, rhodium, cobalt, iron, nickel,rhenium, tungsten and lanthanum.
 39. The method according to claim 31,wherein said ion is cadmium and said fine particles are cadmium sulfide.40. The method according to claim 31, wherein said ion is barium andsaid fine particles are barium sulfate.
 41. The method according toclaim 31, wherein said ion is copper and said fine particles are coppersulfide.
 42. The method according to claim 31, wherein said ion ismanganese and said fine particles are manganese oxide.
 43. The methodaccording to claim 31, wherein said ion is silver and said fineparticles are silver chloride.
 44. The method according to claim 31,wherein said ion is silver and said fine particles are elemental silver.45. The method according to claim 31, wherein said ion is gold and saidfine particles are gold.
 46. The method according to claim 31, whereinsaid ion is selenium and said fine particles are selenium.